PILOT PROJECT CORE As the ?implementation? arm of the PACE, the Pilot Project Core will drive novel discoveries in OUD that are uniquely enabled by PET imaging. Pilot projects will leverage the Radiochemistry Core, Imaging Core, and Clinical Core, and the Administrative Core will support training and career development. The Specific Aims are: (1) to accelerate the science of OUD through a set of inter-related and rigorous pilot projects that leverage the PACE infrastructure. An initial set of vetted pilot projects will elucidate the role of mu- and delta- opioid receptor availability in OUD and its treatment, the influence of genetic variation on receptor availability and therapeutic dosing in OUD, (c) the role of the kappa-opioid receptor in suicidal ideation in OUD, and the mechanistic role of neuroinflammation in OUD with or without HIV; (2) to oversee a fair and transparent process to solicit, review, support, and evaluate innovative and rigorous future pilot projects. Working with the Administrative Core, the Pilot Core will solicit applications on an annual basis beginning in year 2 through direct outreach to Departments and Centers at Penn and Yale, and through campus-wide emails; conduct a scientifically rigorous internal NIH-style review process with transparent merit criteria, provide interdisciplinary mentoring and support, including scientific planning and methodological and technical assistance, and evaluate the success of these efforts; and (3) to train the next generation of addiction PET imaging scientists. These activities include didactic and experiential training in PET imaging, data analysis, and OUD neurobiology, and interdisciplinary co-mentorship and career development opportunities. Training initiatives will attract and support both early-stage investigators and established investigators who wish to incorporate PET imaging into addiction research. Finally, an annual PACE Research Day will convene Penn's active PET researchers, the PACE's Internal and External Advisory Boards, and new investigators to share the latest research findings and to encourage collaborations with the new P30 PET tools.